Nature Based Infrastructure
What is nature based infrastructure? Is it just a fancy name for a world without concrete?
The landscapes we live in determine the kinds of risks we face during inclement weather and natural disasters. Communities at the bottom of large watersheds may be at risk of flooding. Coastal regions may be at risk of damage from storm surges.
The first step to any project is to clearly define the underlying problem that needs to be solved. During this process there is a crucial question that is often overlooked. Does this solution work for the community and environment?
Traditional infrastructure projects look at engineered methods to reducing impact from extreme events. For example, a community that experiences seasonal flooding might look into constructing more storm culverts and concrete channels to divert water around the community. A nature based approach to the same situation might include planting more trees in the surrounding hillsides to help retain more water and reduce the amount of flooding in the nearby town. Every landscape is different, and a nature based approach may require more localized design expertise compared to a traditional engineered solution.
Photo by Nathan Cohen, 2018 - This is an example of an engineered grey infrastructure solution in Japan. Precast concrete units create a barrier to protect the coastline from storm surges and tsunamis.
After the 2011 Tsunami in Japan, cities developed new coastline protection techniques. Some of the best solutions have combined traditional grey infrastructure solutions with nature based solutions. The image below showcases a plan for a tsunami-resistant city in northern Japan. A concrete wall is used as the main barrier for average tsunami sizes; the topography of the coastline and the use of natural features like treed areas add further resilience for extreme events.
Excerpt from Nature 2012, featured in APRU Multi-Hazards Webinar Series presented by Tohoku University in March 2021.
Research on many initiatives around the world continue to show the value of nature based solutions that go beyond the visual appeal. The David Suzuki Foundation features a report outlining an initiative in New Brunswick, Canada that reviewed the benefits of proactive forest management and engineered solutions to reduce the amount of storm water runoff into the St John River. The study was commissioned after years of continued damage to storm culverts and damage to roadways during intense rainstorms. The study looked at the benefits of two predominantly forested watersheds in the same region.
The value of the forested areas for storm water retention was estimated to be $3.5 to $4.1 million because that would be the cost of building an engineered storm management system if the lands were cleared. The forested areas are not just providing this value for water retention. There are many other benefits to maintaining forested areas. Some of these benefits, like water retention, can be quantified. Many other benefits are present, but do not as easily translate to dollar figures on a page.
The Nature-Based Infrastructure Global Resource Centre recently issued an economic valuation of maintaining the Hondbossche Dunes in the Netherlands. The existing sea dike in the northern Netherlands no longer met the required safety standards. Instead of raising the height of the existing sea dike, policy makers decided to construct an artificial dune system 7km in length along the coast. The dunes are a nature based coastal protection system.
The report considered the cost-benefit of the sand dunes (nature based infrastructure) and a sheet pile wall (grey infrastructure) solution. Based on continued measurement, the natural dune structure will grow in size overtime due to prevailing winds, and will become more resilient as natural grasses continue to grow and reinforce the landscape.
The following graph shows the net present value of each solution under various scenarios. In all projections, the natural dune project is a more effective use of money in order to protect the coastline, as seen in figure 8 below.
Excerpt from “ Sustainable Asset Valuation (SAVi) of Nature-Based Coastal Protection in the Netherlands.”, 2021 International Institute for Sustainable Development.
There are many benefits to building with nature as opposed to building on top of nature. Two examples of nature based solutions have been presented here, but there are many more projects that are being researched and evaluated around the world to show the benefits of nature based infrastructure.
When the cost-effective solution is also better for the environment, everyone wins.
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References:
David Suzuki Foundation - Natural Asset Evaluation - New Brunswick
International Institute for Sustainable Development - Hondbossche Dunes
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